scholarly journals Particle Size Variation and Prediction of Molecular Weight of Bi(III) Hydrolyzed Polymer Using Light Scattering Technique

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
N. Priyadarshini ◽  
M. Sampath ◽  
Shekhar Kumar ◽  
U. Kamachi Mudali
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Light Scattering ◽  
Second Virial Coefficient ◽  
Size Variation ◽  
Degree Of Polymerization ◽  
High Concentration ◽  
Naoh Solution ◽  
Colloid Formation ◽  
Light Scattering Technique

The present paper gives an overview of the hydrolysis reactions up to colloid formation of Bi(III) in aqueous nitric acid medium using light-scattering measurements. The hydrolysis products of Bi were polynuclear complexes such as dimers, pentamers, and the most important is the hexameric species. In the present investigation Bi3+ polymers were prepared by diluting different concentrations of Bi(NO3)3·5H2O solutions to pH 1 ± 0.1 by adding 0.1 M NaOH solution as it starts to precipitates at pH 1.4. The degree of polymerization was found to be 5-6 units. Particle size measurements were performed, and it has been found that particle size increases at high concentration of Bi due to aggregation. Refractive index measurements were also performed. The molecular weight of hydrolyzed polymeric species of Bi was determined by using Debye plot, and it was estimated as 1236 Da. The second virial coefficient was found to be 6.24 × 10−3 mLg−1 Da. The present investigation confirms that the predominant complex in the solution has 5-6 Bi atoms.

Size, Form and Flexibility of the Rubber Molecule

1962 ◽  
Vol 35 (4) ◽  
pp. 908-917 ◽  
Author(s):  
G. V. Schulz ◽  
A. Mula
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Light Scattering ◽  
Virial Coefficient ◽  
Second Virial Coefficient ◽  
Quantitative Measure ◽  
Degree Of Polymerization ◽  
Bromine Content ◽  
Angle Scattering ◽  
Gaussian Density

Abstract Natural rubber can be brominated in dilute cyclohexane solution, whereby the molecular weight, corresponding to the bromine content, increases. For brominated rubber, increasing bromine content makes cyclohexane an increasingly poorer solvent, which is shown by a contraction of the molecule coils and a decrease in the second virial coefficient. Quantitative results were obtained through viscosity and light scattering measurements. Cyclohexane solutions of brominated rubber containing about 43% bromine have a θ point at room temperature. Here the second virial coefficient is zero and the coil has an ideal Gaussian density distribution. In this state the coil diameter is about 1.6 times bigger than for completely free rotation. A comparison of these data with X-ray low angle scattering could yield a quantitative measure of possible molecular branching. Brominated rubber with about one bromine per isoprene residue is a good starting material for the preparation of electron-microscope samples which can be used for the determination of the molecular weight distribution in rubber. The value of the weight average degree of polymerization determined by an electron microscope is in agreement with that determined through (1) light scattering and (2) ultracentrifuge and diffusion measurements. The molecular inhomogeneity of our sample is of the order of 0.5.

scholarly journals Probing Uranium(IV) Hydrolyzed Colloids and Polymers by Light Scattering

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
N. Priyadarshini ◽  
M. Sampath ◽  
Shekhar Kumar ◽  
U. Kamachi Mudali ◽  
R. Natarajan
Keyword(s):  
Light Scattering ◽  
Virial Coefficient ◽  
Average Molecular Weight ◽  
Second Virial Coefficient ◽  
Solvent Interaction ◽  
Stable Suspension ◽  
Crystalline Nature ◽  
Hydrolysis Of ◽  
Colloid Formation ◽  
Light Scattering Technique

Tetravalent uranium readily undergoes hydrolysis even in highly acidic aqueous solutions. In the present work, solutions ranging from 0.4 to 19 mM (total U) concentration (1<pH<4) are carefully investigated by light scattering technique with special emphasis on polymerization leading to colloid formation. The results clearly indicate that the concentration has significant effect on particle size as well as stability of colloids. With increasing concentration the size of colloids formed is smaller due to more crystalline nature of the colloids. Stability of colloids formed at lower concentration is greater than that of colloids formed at higher concentration. Weight average molecular weight of the freshly prepared and colloidal polymers aged for 3 days is determined from the Debye plot. It increases from 1,800 to 13,000 Da. 40–50 atoms of U are considered to be present in the polymer. Positive value of second virial coefficient shows that solute-solvent interaction is high leading to stable suspension. The results of this work are a clear indication that U(IV) hydrolysis does not differ from hydrolysis of Pu(IV).

Solution Properties of Polybutadiene and trans-Polyisoprene Fractions

1963 ◽  
Vol 36 (2) ◽  
pp. 488-501
Author(s):  
W. Cooper ◽  
D. E. Eaves ◽  
G. Vaughan
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Benzene Solution ◽  
Second Virial Coefficient ◽  
Virial Coefficients ◽  
Γ Radiation ◽  
Branched Polymer ◽  
Butyl Lithium ◽  
Second Virial Coefficients ◽  
Molecular Weights

Abstract Linear polybutadienes, prepared with butyl lithium as catalyst, and polybutadienes branched by exposure to γ-radiation have been fractionated and the fractions examined by osmometry and light scattering. Turbidimetric second virial coefficients (A2τ) of mixed polymer fractions are virtually the same as those of the higher molecular weight components of the mixtures for most compositions. This is true both for mixtures of linear with linear and linear with branched polymer. The higher the molecular weight of the fraction, the greater the effect; the addition of 1 per cent microgel to a linear polymer reduced A2τ by a factor of three. The presence of microgel or high molecular weight branched polymer has been shown to be responsible for the very high molecular weights previously reported for polybutadienes from light scattering measurements. It is conveniently removed by shaking the solutions with calcium sulfate. Second virial coefficients obtained either by light scattering or osmometry are, within the limits of experimental error, uninfluenced by branching in the polymer. In general those factors which lead to increased branching also result in increased polydispersity, and it is the latter which results in the decrease in A2τ. The fall of the osmotic second virial coefficient (A2τ) with molecular weight is much smaller than would be calculated theoretically, and the fall in A2τ is greater than would be expected, notwithstanding the fact that for some of the fractions Mw/Mn&lt;1.1. This indicates that A2τ is sensitive to the low molecular weight species present in the fractions, whereas the reverse must apply to A2τ. Natural or synthetic trans-polyisoprene showed analogous behavior to polybutadiene, although, owing to experimental difficulties, sharp branched fractions could not be obtained. The following viscosity-molecular weight relationships were obtained in benzene solution: [η]=1.45×10−4M0.76 for butyl lithium-catalyzed polybutadienes, and [η]=4.37×10−4M0.65 for natural and synthetic trans-polyisoprenes.

Development of Polymeric Micro/Nanostructures For Gene Delivery

2007 ◽  
Vol 1019 ◽  
Author(s):  
Dania Alyounes ◽  
Christopher Yengo ◽  
Tim Doran ◽  
Qi Lu ◽  
Kenneth Gonsalves
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Light Scattering ◽  
Binding Affinity ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Fluorescence Studies ◽  
Molecular Weights ◽  
Fluorescence Techniques ◽  
Exponential Increase

AbstractPluronic® polymers were screened for binding affinity to oligoribonucleotides (ORN) using fluorescence techniques. F127 (Mw 12600 g/mole) proved to have the strongest binding affinity. Urethane linkages were introduced into F127 and two other Pluronics, F38 (Mw 4700 g/mole) and F77 (Mw 6600 g/mole) to prepare polymers that were multiples of their respective initial molecular weights. A series of these polyurethane Pluronics were screened for binding affinity. Fluorescence studies showed a relationship between the molecular weight of the PO units and the binding affinity in the structures of the newly synthesized polyPluronics, especially in the case of F77. Light scattering confirmed the binding affinity between the ORN and F77 polymers. Particle size analysis showed an exponential increase until the critical micelle concentration. Other analogs of these polymers also studied for their binding affinity were poly(ester amines) and PINC.

scholarly journals Flame Retardant Submicron Particles via Surfactant-Free RAFT Emulsion Polymerization of Styrene Derivatives Containing Phosphorous

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1244
Author(s):  
Taeyoon Kim ◽  
Joo-Hyun Song ◽  
Jong-Ho Back ◽  
Bongkuk Seo ◽  
Choong-Sun Lim ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Flame Retardant ◽  
Emulsion Polymerization ◽  
Degree Of Polymerization ◽  
Submicron Particles ◽  
Poly Ethylene Glycol ◽  
Raft Agent ◽  
Flame Retardant Properties ◽  
Poly Ethylene

The reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization of diethyl-(4-vinylbenzyl) phosphate (DEVBP) was performed using PEG-TTC as a macro RAFT agent. PEG-TTC (MW 2000, 4000) was synthesized by the esterification of poly (ethylene glycol) methyl ether with a carboxylic-terminated RAFT agent, composed a hydrophilic poly (ethylene glycol) (PEG) block and a hydrophobic dodecyl chain. The RAFT emulsion polymerization of DEVBP was well–controlled with a narrow molecular size distribution. Dynamic light scattering and confocal laser scanning microscopy were used to examine the PEG-b-PDVBP submicron particles, and the length of the PEG chain (hydrophilic block) was found to affect the particle size distribution and molecular weight distribution. The submicron particle size increased with increasing degree of polymerization (35, 65, and 130), and precipitation was observed at a high degree of polymerization (DP) using low molecular weight PEG-TTC (DP 130, A3). The flame retardant properties of the PEG-b-PDVBP were evaluated by thermogravimetric analysis (TGA) and micro cone calorimeter (MCC). In the combustion process, the residue of PEG-b-PDEVBP were above 500 °C was observed (A1 ~ B3, 27 ~ 38%), and flame retardant effect of PEG-b-PDEVBP submicron particles/PVA composite were confirmed by increasing range of temperature and decreasing total heat release with increasing contents of PEG-b-PDEVBP. The PEG-b-PDEVBP submicron particles can provide flame retardant properties to aqueous, dispersion and emulsion formed organic/polymer products.

Sign in / Sign up

Export Citation Format

Share Document